Sound Deadening / Insulation

[ivor Fastun 0]

Post matrix replacement im now thinkin about replacing the undercarpet insulation, the re-cycled cotton stuff and sandbags were in no state to re-use.

 

Ive had a look about dynomat and stuff like that, it sounds to me like that works by deadening sound by making a thicker substance to pass through and you would need some insulation to go with it.

 

I stumbled across a thread about this elsewhere and someone recommended using flashing tape instead of dynomat. Its the stuff used to seal flat roofs etc. Tis basically the same stuff, aluminium backed self adhesive bitumen layer, only difference i can see is the price. You can get enough to cover your floor pans for £30 from BnQ! Its only about 2-3mm thick too.

 

Im thinking about using this, then some self adhesive sound insulation foam from http://www.rswww.com £13 psm to redo my floorpans. The foam is high-density, lightweight and aluminum backed too.

 

Has anyone else experimented like this before? There is no way im putting the same stuff back in that i took out, it was dropping to bits!!

[dinkus 10]

If you're looking for sound insulation, then heavy stuff and foamy stuff will do the trick. The roof flashing stuff is exactly the same as Dynamat/Skinz/et al, but as you say it's only 2-3mm thick rather than 4-6mm thick.

 

Skinz is really not all that expensive if you buy it in big sheets from a car audio place. Buying the pre-packaged stuff off the shelf in Halfords is tho.

 

However, if you're replacing the under-carpet insulation you also have to bear in mind the amount of sealing wax under there. The chassis was wax-dipped at the factory to stop rust later in the car's life. If you scrape all of that off (pain in the bum in itself) then you've lost the rustproofing.

 

Similarly, you'll want some fairly good heat insulation down there, which is why there's all that matted fibre stuff. You could use some foam instead I guess tho.

 

Then you're somewhat back to square 1 tho - for the sound deadening stuff like Dynamat to work properly, you need to stick it to the metal to stop the metal from vibrating. If you just lay it on top of a layer of foam, it'lll still kill the sound a fair amount, but the edges will vibrate against the bodywork - so make sure they're foam-covered.

[chimo 0]

not sure about the product called 'brown bread'.. seems popular at home and was cheaper than dynomat... don't know about the ease of instalation.